Antibiotic Resistance Profiles and Biofilm Formation of Pseudomonas aeruginosa Isolates from Hospitalized Patients in Sulaymaniyah Governorate, Iraq

Abstract

Pseudomonas aeruginosa (P. aeruginosa) is a highly adaptable opportunistic pathogen responsible for a wide range of hospital-acquired infections, particularly in immunocompromised and critically ill patients. This study investigated the clinical distribution, antimicrobial resistance patterns, biofilm formation capacity, and hemolysin production of P. aeruginosa isolates collected from hospitalized patients in Sulaymaniyah governorate, Iraq. A total of 85 isolates were recovered from 168 clinical specimens, including burn wound swabs (54.1%), endotracheal aspirates (21%), urine samples (14.1%), and various body fluids. The majority of isolates were obtained from male patients (56%), primarily aged 21–40 years, with a higher prevalence in general wards (70.6%) compared to intensive care units (29.4%). Identification and antimicrobial susceptibility testing were performed using standard microbiological methods and the VITEK 2 system. Biofilm production was assessed using the microtiter plate method, while hemolysin activity was evaluated on 5% sheep blood agar. A high prevalence of biofilm formation was observed (96.5%), with 76.5% of isolates producing strong or moderate biofilms. Antimicrobial resistance profiling revealed high resistance rates to erythromycin (96.5%), ampicillin/sulbactam (95.3%), and co-trimoxazole (77.6%), while colistin demonstrated the lowest resistance rate (29.4%). Multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR) profiles were identified in 72.9%, 18.8%, and 5.9% of isolates, respectively. A strong association was found between biofilm strength and resistance to multiple antibiotic classes, particularly β-lactams, fluoroquinolones, and sulfonamides. Furthermore, β-hemolysin production was more frequently observed among strong and moderate biofilm producers, suggesting a potential link between biofilm formation, virulence factor expression, and antimicrobial resistance. These findings highlight the significant clinical burden posed by MDR P. aeruginosa and underscore the importance of routine surveillance for biofilm formation and resistance markers to guide more effective infection control and therapeutic strategies in healthcare settings.